Semiconductor device for ambient sensing including a cavity and a mechanical filtering structure

ABSTRACT

A semiconductor device for ambient sensing including: a cap traversed by a hole; and a main body mechanically coupled to the cap so as to delimit a cavity, which is interposed between the main body and the cap. The main body includes a semiconductor body and a coupling structure, which is interposed between the semiconductor body and the cap and laterally delimits a channel, which fluidically couples the cavity and the hole. The channel performs a mechanical filtering that is finer than the mechanical filtering performed by the hole.

BACKGROUND Technical Field

The present disclosure relates to a semiconductor device for ambientsensing, which includes a cavity that can be coupled to the externalworld and a mechanical filtering structure; moreover, the presentdisclosure regards a corresponding manufacturing process.

Description of the Related Art

As is known, numerous sensors known as ambient sensors are currentlyavailable, which supply electrical signals representing parameters ofthe environment in which they are positioned, such as for examplepressure, temperature, humidity, presence of gas, etc. Inter alia,semiconductor devices that function as ambient sensors are known.

BRIEF SUMMARY

The present disclosure is directed to at least one embodiment of asemiconductor device, that includes a cavity, a cap, a hole extendingthrough the cap, the hole having a diameter or a dimension, a main bodycoupled to the cap so as to delimit the cavity between the main body andthe cap. The main body includes a semiconductor body, a couplingstructure on the semiconductor body, the coupling structure between thesemiconductor body and the main body, and a channel fluidically couplesthe hole to the cavity, the channel is laterally delimited by thecoupling structure, the channel includes a first sidewall and a secondsidewall opposite to the first sidewall, the filtering channel has adimension that extends from the first sidewall to the second sidewall,the dimension is less than the diameter of the hole. The hole isconfigured to provide a first filtering and the channel is configured toprovide a second filtering that is finer than the first filtering by thehole.

The present disclosure is also directed to a semiconductor device,includes a cap, a filtering hole that extends through the cap, where thefiltering hole has a diameter. The semiconductor device includes acavity and a main body coupled to the cap so as to delimit the cavitybetween the main body and the cap. The main body includes asemiconductor body, a coupling structure between the semiconductor bodyand the cap, and a filtering channel fluidically couples the cavity andthe hole, the filtering channel is laterally delimited by the couplingstructure, the filtering channel has a first sidewall and a secondsidewall opposite to the first sidewall, the filtering channel has adimension that extends from the first sidewall to the second sidewall,the dimension is less than the diameter of the filtering hole. Thesemiconductor device includes a first opening delimited by the channel,the first opening in fluid communication with the hole, and a secondopening delimited by the channel in fluid communication with a part ofthe cavity and laterally staggered from the first opening.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a better understanding of the present disclosure, preferredembodiments thereof will now be described, purely by way of non-limitingexample, with reference to the attached drawings, wherein:

FIG. 1 is a schematic illustration of a portion of a cross-section of anambient sensing device of a known type;

FIG. 2 is a schematic illustration of a portion of a cross-section of anembodiment of the present sensing device;

FIG. 3 is a schematic illustration of a cross-section of the sensingdevice represented in FIG. 2 , taken along a plane shown in FIG. 2 ;

FIG. 4 is a schematic top view of a further embodiment of the presentsensing device, with portions removed;

FIG. 5 is a schematic illustration of a portion of a cross-section of afirst semiconductor wafer, during a step of a manufacturing process;

FIG. 6 is a schematic illustration of a portion of a cross-section of asecond semiconductor wafer, during a step of the manufacturing process;and

FIGS. 7 and 8 are schematic illustrations of a portion of across-section of a set of two semiconductor wafers, during twosuccessive steps of the manufacturing process.

DETAILED DESCRIPTION

FIG. 1 shows a portion of a section of a sensing device 1 that comprisesa semiconductor body 2, which in turn comprises a substrate 3, made, forexample, of silicon, and an overlying epitaxial region 4, formed by oneor more epitaxial layers and defining a first surface S4, which delimitsthe semiconductor body 2 at the top.

The sensing device 1 further comprises a first passivation layer 6,formed by a dielectric material (for example, oxide) and arranged on thefirst surface S4, and a second passivation layer 8, formed by adielectric material (for example, nitride) and arranged on the firstpassivation layer 6.

The sensing device 1 further comprises a plurality of metallizations,which extend in the region formed by the first and second passivationlayers 6, 8. For instance, a first bottom metallization 10 and a firsttop metallization 12, which are made of metal material, are visible inFIG. 1 . The first bottom metallization 10 is arranged on the firstsurface S4, in contact with the epitaxial region 4, and is overlaid bythe first passivation layer 6. The first top metallization 12 isarranged on the first passivation layer 6 and overlies, at a distance,the first bottom metallization 10. In addition, the second passivationlayer 8 in part overlies the first top metallization 12. In particular,the second passivation layer 8 extends over the first top metallization12 so as to leave a part of the latter exposed, i.e., so as to define awindow 14 that faces the exposed part of the first top metallization 12,referred to in what follows as the sealing window 14.

The sensing device 1 further comprises an active area 15, whichtypically extends from the first surface S4, within an underlyingportion of the epitaxial region 4 and within a substrate portion 3underlying the latter. The active area 15 is coated with the first andsecond passivation layers 6, 8 and is typically laterally staggered withrespect to the metallizations. Furthermore, albeit not illustrated, theactive area 15 may be electrically connected to the first bottommetallization 10 and/or to further electrical terminals (notillustrated), which are designed to enable the electrical connection tothe external world. The first top metallization 12 may have anelectrical function (for example, it may be connected to the ground ofthe sensing device 1) or may be without any electrical function.

In practice, the semiconductor body 2 and the first and secondpassivation layers 6, 8 form a main body 17 of the sensing device 1,which is delimited at the top by a second surface S₁₇, formed by thesecond passivation layer 8.

The sensing device 1 further comprises a cap 18 formed by semiconductormaterial (for example, silicon), which overlies, at a distance, the mainbody 17, so as to delimit a cavity 20. In particular, the cap 18comprises a respective primary body 19, which has a planar shape and isdelimited at the bottom by a third surface S₁₈, and a projecting region22, which extends downwards, starting from the third surface Sib, in thedirection of the main body 17. Although visible in FIG. 1 , theprojecting region 22 has a closed and hollow shape (for example, theshape of an annulus or of a rectangular frame) and is arranged so that,in top view (not illustrated), it surrounds the active area 15.Moreover, the projecting region 22 forms a single piece with the primarybody 19 of the cap 18. The first surface S4 faces towards the cap 18.

In greater detail, assuming that the projection 22 has an annular shapeand has, in top view, the shape of an annulus, it includes a first and asecond side wall P₁₁, P₁₂, which define cylindrical profiles, and abottom wall P_(b).

The sensing device 1 further comprises a junction region 23, which isformed, for example, by a germanium-aluminum eutectic alloy and extendsunderneath the bottom wall P_(b) of the projection 22, with which it isin direct contact, until it penetrates partially within the first topmetallization 12.

In practice, the junction region 23 extends within the sealing window14, in contact with the underlying first top metallization 12 so as tofunction as junction between cap 18 and main body 17. For this purpose,also the junction region 23 and the first top metallization 12 arering-shaped; i.e., they have shapes that are closed, in top view, andare hollow.

The projecting region 22, the junction region 23 and the first topmetallization 12 form a ring-like structure that laterally delimits thecavity 20 and acts as a lateral seal. The cavity 20 is moreoverdelimited, at the bottom, by a corresponding portion of the secondpassivation layer 8 that overlies the active area 15. The cavity 20 ismoreover delimited, at the top, by a portion of the primary body 19 ofthe cap 18, which overlies, at a distance, the active area 15. Theactive area 15 may be referred to as an active portion, an activeregion, or some other similar language.

Extending through the primary body 19 of the cap 18 is a hole 25, i.e.,a through cavity, a through hole, or a recess, which sets the cavity 20in fluidic communication with the external world.

In practice, the cavity 20 is sealed, except for the presence of thehole 25, which has, for example, a cylindrical shape.

Once again with reference to FIG. 1 , the complete section of thesensing device 1 can be obtained by flipping over the portionillustrated in FIG. 1 , except for the hole 25.

All this having been said, assuming for example that the sensing device1 acts as pressure sensor, in use the air penetrates into the cavity 20through the hole 25. Furthermore, the active area 15 operates so as tovary at least one electrical quantity, as a function of a parameter (inparticular, the pressure) of the air present in the cavity 20. Thevariation of said electrical quantity represents an electrical signalindicative of the aforementioned parameter, which can be supplied, forexample, to an external processing device (not shown). In particular, inthe case of a pressure sensor, the active area may include a deformablemembrane (not shown) as a function of the pressure in the cavity 20 andis coupled to a piezoelectric, piezoresistive or capacitive sensor (notillustrated).

The hole 25, in addition to enabling access of air (or more in generalof a fluid) into the cavity 20, also functions as a mechanical filter inthe sense that it prevents access to the cavity 20 by undesiredparticles, which could, for example, damage the sensing device 1 or inany case alter the operation thereof. Said filtering function isperformed both during use of the sensing device 1 and prior to use,i.e., during the process of manufacturing of the sensing device 1, forexample during the so-called back-end operations.

Currently, the hole 25 is formed after a first and a secondsemiconductor wafer, which are to form the cap 18 and the main body 17,respectively, have been bonded together, following upon dicingoperations. In this way, however, it is not possible to form holes withdiameters of less than 10 μm. Said lower limit may prove insufficientfor certain applications, such as for example applications that use thecavity 20 to be inaccessible to water. In fact, it is known that, inorder to prevent water from entering the cavity 20, the diameter of thehole 25 should be not greater than (approximately) 1 μm.

FIG. 2 shows an ambient sensing device 50 of the semiconductor type,which, for reasons of brevity and without this implying any loss ofgenerality, is now described with reference to the differences withrespect to the sensing device 1 illustrated in FIG. 1 . Elements alreadypresent in the sensing device 1 shown in FIG. 1 are designated by thesame or similar reference numbers, except where otherwise specified.

In detail, and without this implying any loss of generality, the ambientsensing device 50 comprises a second bottom metallization 30, which isco-planar with the first bottom metallization 10, and is thereforearranged on the first surface S4, in contact with the epitaxial region4, and is overlaid by the first passivation layer 6. Moreover, thesecond bottom metallization 30 is laterally staggered with respect tothe first bottom metallization 10, in the direction of the active area15 so as to be arranged underneath the cavity 20. The first and secondbottom metallizations 10, 30 may or may not be in electrical contact.

The ambient sensing device 50 further comprises a top metallizationstructure 32, which in turn comprises a pair of metallizations, referredto in what follows as the first and second filtering metallizations M1,M2. The first and second filtering metallizations M1, M2 may be referredto as metal layers, metallization layers, filtering metallizationlayers, or filtering metallization portions.

The first and second filtering metallizations M1, M2 are co-planar andare arranged laterally staggered over the part of first passivationlayer 6 that coats the second bottom metallization 30.

In detail, the first and second filtering metallizations M1, M2 have asame thickness (for example, equal to 1 μm), are made, for example, ofaluminum, and are laterally staggered so as to delimit a channel 35having an elongated shape, which extends in a direction parallel to anaxis X of an orthogonal reference system XYZ such that the plane XY isparallel to the first surface S4.

In greater detail, as shown in FIG. 3 , the first and second filteringmetallizations M1, M2 have, for example, shapes symmetrical with respectto a plane of symmetry SP, parallel to the plane XZ. In addition, thefirst and second filtering metallizations M1, M2 are delimited,respectively, by a first and a second side wall P1, P2, which have theshape of rectangles parallel to the plane ZX and face one another. Thefirst and second side walls P1, P2, laterally delimit the channel 35;furthermore, the channel 35 is delimited at the bottom by the firstpassivation layer 6.

Moreover, the first and second filtering metallizations M1, M2 are alsolaterally delimited by a third and a fourth side wall P3, P4,respectively, each of which has, for example, a curved shape with singleconcavity, with concavities opposite to one another. Without thisimplying any loss of generality, the first and second filteringmetallizations M1, M2 have a shape of two half-shells arranged in frontof one another, the envelope of which defines, approximately and in topview, a flattened ellipse along the minor axis. In addition, the firstand second filtering metallizations M1, M2 are delimited at the top,respectively, by a first and a second top surface T1, T2, which aremutually co-planar and parallel to the plane XY.

The second passivation layer 8 coats a peripheral portion of theensemble formed by the first and second filtering metallizations M1, M2so as to delimit a window 40, referred to in what follows as a filteringwindow 40. The filtering window 40 may be referred to as a filteringopening, a filtering channel, or a filtering space.

The filtering window 40 has a closed shape, in top view, and faces thefirst and second top surfaces T1, T2; for example, the filtering window40 has an approximately elliptical shape. In particular, the secondpassivation layer 8 extends on peripheral portions of the first andsecond top surfaces T1, T2, and hence covers the third and fourth sidewalls P3, P4, whereas the filtering window 40 faces central portions ofthe first and second top surfaces T1, T2. The filtering window 40 thenleaves the first and second side walls P1, P2, and hence the channel 35,exposed. The filtering window 40 has a first portion that is overlappingthe first metallization M1 and a second portion that is overlapping thesecond metallization M2. The first and second portions having a U-shape.

The cap 18 further comprises a projecting region 42, referred to in whatfollows as the projecting filtering region 42. The projecting filteringregion 42 may be referred to as a projecting portion, a protrudingregion, a protruding portion, an extension region, or an extensionportion.

The projecting filtering region 42 extends downwards, starting from thethird surface S₁₈, in the direction of the main body 17. Moreover, theprojecting filtering region 42 is made of the same material (forexample, a semiconductor) as the primary body 19 of the cap 18, withwhich it forms a single piece.

In greater detail, as may be seen in FIG. 3 , in top view the projectingfiltering region 42 has, for example and to a first approximation, theshape of a flattened ellipse along the minor axis so as to form aprofile including two parallel segments, the ends of which are connectedby a pair of curved lines.

In addition, the projecting filtering region 42 extends at the bottomuntil it partially penetrates into the filtering window 40. In thisconnection, without this implying any loss of generality, the projectingfiltering region 42 has a cross-section with an area smaller than thearea of the filtering window 40 and extends within the latter, withoutcontacting the second passivation layer 8, hence without contacting theedge of the filtering window 40. These areas of the cross-sections ofthe projecting filtering region 42 and the filtering window 40 may bereferred to as cross-sectional areas or some other similar language.Furthermore, the projecting filtering region 42 is delimited, at thebottom, by a surface 44 (referred to in what follows as the couplingsurface 44), which is parallel to the plane XY and overlies, in directcontact, the first and second top surfaces T1, T2 of the first andsecond filtering metallizations M1, M2. The projecting filtering region42 is coupled to the first and second filtering metallizations M1, M2.

The hole 25 extends not only through the primary body 19 of the cap 18but also through the projecting filtering region 42, until the hole 25gives out onto or terminates at the coupling surface 44. Purely by wayof example, the hole 25 has an axis (designated by Z′ in FIGS. 2 and 3), which lies in the plane of symmetry SP. To a first approximation, theaxis (not shown) of the channel 35 is parallel to the axis X and lies inthe plane of symmetry SP.

Without this implying any loss of generality, the projecting filteringregion 42 and the filtering window 40 each have shapes symmetrical withrespect to the plane of symmetry SP. Moreover, in the embodimentillustrated in FIG. 3 , the channel 35 is symmetrical with respect tothe plane of symmetry SP; in particular, the channel 35 has the shape ofa parallelepiped.

The ambient sensing device 50 further comprises a first and a secondjunction region G1, G2, which are made, for example, of analuminum-germanium eutectic alloy and are approximately symmetrical withrespect to the plane of symmetry SP. The first and second junctionregions G1, G2 fix the projecting filtering region 42 to the topmetallization structure 32.

In greater detail, the first junction region G1 is interposed, in directcontact, between the projecting filtering region 42 and the firstfiltering metallization M1. In particular, a bottom portion of the firstjunction region G1 extends underneath the first top surface T1, andhence also underneath the coupling surface 44, within the firstfiltering metallization M1, whereas a top portion of the first junctionregion G1 extends above the first top surface T1, and hence also abovethe coupling surface 44, within the projecting filtering region 42.

Likewise, the second junction region G2 is interposed, in directcontact, between the projecting filtering region 42 and the secondfiltering metallization M2. In particular, a bottom portion of thesecond junction region G2 extends underneath the second top surface T2,and hence also underneath the coupling surface 44, within the secondfiltering metallization M2, whereas a top portion of the second junctionregion G2 extends above the second top surface T2, and hence also abovethe coupling surface 44, within the projecting filtering region 42.

Without this implying any loss of generality, the first and secondjunction regions G1, G2 have planar shapes and are separate from oneanother. In top view, the first and second junction regions G1, G2 arearranged on opposite sides of the channel 35, as well as at a distancefrom the channel 35 and from the hole 25.

In greater detail, the dimension of the hole 25, denoted by D, is, forexample equal to 10 μm. Moreover, the width of the channel 35, denotedby d, understood as the distance between the first and second side wallsP1, P2, may be less than 10 μm and equal, for example, to 1 μm. Inaddition, the channel 35 has a height, measured in a direction parallelto the axis Z, equal to the thickness of the first and second filteringmetallizations M1, M2, and hence, as mentioned previously, for exampleequal to 1 μm. The first and second junction regions G1, G2 have athickness (in a direction parallel to the axis Z) for example of 1. Insome embodiments, the hole 25 may have a circular, rectangular, square,diamond, or some other type of shape or cross-section. When the hole 25has the circular shape, the dimension D is a diameter, which can beclearly seen in FIG. 3 . When the hole has the rectangular shape, thedimension D may extend from a first sidewall of the rectangle to asecond sidewall of the rectangle opposite to the first sidewall. Whenthe hole is has the diamond shape, the dimension D may extend from afirst point to a second point opposite to the first point.

The channel 35 hence has a cross-section (in planes parallel to theplane ZY), which is approximately rectangular and has an area smallerthan the area of the cross-section (in planes parallel to the plane XY)of the hole 25. These areas of the cross-sections of the hole 25 and thechannel 35 may be referred to as cross-sectional areas or some othersimilar language.

Once again with reference to the hole 25, a bottom portion thereof facesan underlying portion of the channel 35, with which it is hence influidic communication. In greater detail, as shown in FIG. 3 , thechannel 35 comprises a central portion 36, through which the axis Z′passes; said central portion 36 is overlaid by the hole 25.

Furthermore, the channel 35 comprises a first and a second intermediateportion 37′, 37″, which are arranged in a symmetrical way with respectto the central portion 36, to which they are adjacent. The first andsecond intermediate portions 37′, 37″ are closed at the top bycorresponding portions of the projecting filtering region 42.

The channel 35 further comprises a first and a second peripheral portion38′, 38″, which are adjacent, respectively, to the first and secondintermediate portions 37′, 37″. The first and second peripheral portions38′, 38″ are symmetrical with respect to the ensemble formed by thecentral portion 36 and the first and second intermediate portions 37′,37″. Moreover, in top view, the first and second peripheral portions38′, 38″ are arranged on the outside of the projecting filtering region42.

In greater detail, while the projecting filtering region 42 occupies acentral portion of the filtering window 40, the first and secondperipheral portions 38′, 38″ of the channel 35 face correspondingperipheral portions of the overlying filtering window 40, whichcommunicate with the cavity 20. In turn, the cavity 20 is coupled to thehole 25 through the first and second peripheral portions 38′, 38″ of thechannel 35, which define corresponding lateral openings of the channel35, which face upwards (designated, respectively, by A_(e1) and A_(e2)in FIG. 3 ). The channel 35 is moreover centrally coupled to the hole 25through a corresponding opening defined by the central portion 36(designated by A_(i)), said opening A_(i) also facing upwards.

Purely by way of example, the first and second peripheral portions 38′,38″ of the channel 35 have a length (measured in a direction parallel tothe axis X) for example, of 10 μm.

Operatively, the first and second filtering metallizations M1, M2, thefiltering window 40, the first and second junction regions G1, G2 andthe projecting filtering region 42 form a filtering structure 99 (FIG. 2), which sets the cavity 20 in fluidic communication with the hole 25,and hence enables a fluid present in the external world to penetrateinto the cavity 20 so as to enable the active area 15 to vary, forexample, the value of at least one electrical parameter, as a functionof a chemical or physical characteristic of the fluid, and thus enablemeasurement of this characteristic. In addition, on account of the smallcross-section of the channel 35, the filtering structure 99 acts as amechanical filter, which prevents entry into the cavity 20 of undesiredparticles, which, according to the application and the consequent sizingof the channel 35, may include solid particles, fluid particles (forexample, drops of water), etc. In particular, on account of the smallcross-section, the channel 35 performs a mechanical filtering that isfiner than would be obtained by just the hole 25.

Once again with reference to the filtering capacity of the filteringstructure 99, this enables the hole 25 to have the dimensions that canbe obtained using current manufacturing processes since the task offiltering is not performed by the hole 25. Furthermore, the filteringstructure 99 may be produced by means of so-called front-endmanufacturing techniques, as described hereinafter.

Embodiments that include a number of channels are moreover possible, asshown for example in FIG. 4 , where an ambient sensing device 100 isillustrated, which is now described as regards the differences withrespect to the ambient sensing device 50. For simplicity ofrepresentation, FIG. 4 does not illustrate the second passivation layer8.

In detail, the top metallization structure, here designated by 132comprises eight filtering metallizations, designated, respectively, byM1′-M8′, which are planar and mutually co-planar, have the samethickness, and are made of a same metal material (for example,aluminum).

The filtering metallizations M1′-M8′ are arranged angularly so thatadjacent filtering metallizations delimit a corresponding channel; thechannels are here designated by CH1-CH8.

To a first approximation, in top view the filtering metallizationsM1′-M8′ have the shape of wedges of a region equal to the envelope ofthe filtering metallizations M1′-M8′, each of these wedges beinglaterally delimited by corresponding pairs of rectangular plane sidewalls that depart from a corresponding vertex. In particular, the wedgeof the i-th filtering metallization Mi′ is delimited by a respectivefirst side wall Pi1 and by a respective second side wall Pi2. The i-thchannel CHi is laterally delimited by the first side wall and the secondside wall, which delimit, respectively, a first and a second filteringmetallization that are angularly adjacent to one another, said first andsecond side walls being parallel to one another.

Without this implying any loss of generality, the axes (not illustrated)of the channels CH1-CH8 are angularly equispaced, with a spacing of 45°.

In practice, the channels CH1-CH8 depart radially, in a symmetrical waywith respect to the axis Z′, starting from a central volume 150,arranged underneath the hole 25, and on which the vertices of thewedge-like shapes of the filtering metallizations M1′-M8′ face.

The projecting filtering region, here designated by 142, has, forexample, a cylindrical shape, in which the hole 25 extends, whichoverlies the aforementioned central volume 150.

With reference for brevity only to the first channel CH1 (but the sameconsiderations apply to the other channels CH2-CH7), the hole 25overlies a corresponding central portion (designated by CH1′), which isadjacent to the central volume 150; the central portion CH1′ hencecommunicates with the hole 25. In addition, the projecting filteringregion 142 closes, at the top, an intermediate portion CH1″ of the firstchannel CH1, which is interposed between the central portion CH1′ and aperipheral portion CH1′″ of the first channel CH1. In top view, theperipheral portion CH1′″ is arranged on the outside of the projectingfiltering region 142, within the filtering window, designated by 140 inFIG. 4 (where for simplicity the filtering window 140 is assumed tocoincide, in top view, with the envelope of the filtering metallizationsM1′-M8′). In practice, whereas the projecting filtering region 142occupies a central portion of the filtering window 140, the peripheralportion CH1′″ of the first channel CH1 faces a corresponding peripheralportion of the overlying filtering window 140, so as to communicate withthe cavity 20 (not illustrated in FIG. 4 ). The cavity 20 is hencecoupled to the hole 25 through the central portion CH1′ and theperipheral portion CH1′″ of the first channel CH1, which definecorresponding lateral openings of the first channel CH1, facing upwardsand designated, respectively, by A_(i)′ and A_(e)′.

The ambient sensing device 100 further comprises, for each filteringmetallization M1′-M8′, a corresponding junction region G1′-G8′, which ismade, for example, of a germanium-aluminum eutectic alloy and isinterposed, in direct contact, between the corresponding filteringmetallization M1′-M8′ and the projecting filtering region 142. Withoutthis implying any loss of generality, to a first approximation thejunction regions G1′-G8′ are angularly equispaced and are arranged, intop view, outside of the hole 25.

In greater detail with reference, for simplicity, to just the firstfiltering metallization M1′ and to the first junction region G1′ (butthe same considerations apply to the other filtering metallizationsM2′-M8′ and the other junction regions G2′-G8′), and referring to thefirst top surface T1′ to indicate the surface that delimits the firstfiltering metallization M1′ at the top, and referring to the couplingsurface 144 to indicate the surface that delimits the projectingfiltering region 142 at the bottom, what is described hereinafteroccurs.

The coupling surface 144 and the first top surface T1′ are approximatelyco-planar since the projecting filtering region 142 contacts the firstfiltering metallization M1′. Furthermore, albeit not shown, a bottomportion of the first junction region G1′ extends underneath the firsttop surface T1′, within the first filtering metallization M1′, whereas atop portion of the first junction region G1′ extends above the first topsurface T1′, within the projecting filtering region 142, similarly towhat is illustrated in FIG. 2 .

The width of each of the channels CH1-CH8 (measured in a directionperpendicular to the radial direction) is, for example, equal to theaforementioned width d. Moreover, the channels CH1-CH8 perform the samefunction of mechanical filtering as that performed by the channel 35 ofthe embodiment illustrated in FIGS. 2 and 3 , affording the sameadvantages.

The embodiments described envisage fluidic coupling of the cavity 20 tothe hole 25, through one or more channels, each of which has at least asection, in a plane perpendicular to its own direction of extension,that has an area smaller than the area of the section of the hole 25that has the minimum area from among the sections of the hole 25 inplanes perpendicular to the direction of extension of the hole 25. Inaddition, or as an alternative, it is possible for the function of finefiltering to be performed by at least one of the aforementionedupward-facing openings of the channel, in which case said opening/shas/have an area smaller than the area of the section of the hole 25that has the minimum area from among the sections of the hole 25 inplanes perpendicular to the direction of extension of the hole 25.

Advantageously, the present ambient sensing device can be manufacturedby implementing the following manufacturing process, which is describedwith reference, by way of example, to manufacturing of the ambientsensing device illustrated in FIGS. 2 and 3 .

As shown in FIG. 5 , initially a first semiconductor wafer 200 isprovided, which is machined so as to form the main body 17. As a result,the first wafer 200 comprises the semiconductor body 2, the first andsecond bottom metallizations 10, 30, the first top metallization 12, thetop metallization structure 32, the first and the second passivationlayer 6, 8. In addition, the first wafer 200 comprises the sealingwindow 14 and the filtering window 40.

Furthermore, the first wafer 200 comprises the channel 35, which is, infact, formed using so-called front-end techniques, by means ofappropriate spacing of the first and second filtering metallizations M1,M2.

Moreover, as shown in FIG. 6 , a second semiconductor wafer 202 isprovided, which forms the cap 18. In particular, the second wafer 202 ismachined so as to form the primary body 19, the projecting region 22,the projecting filtering region 42 and the hole 25.

The projecting filtering region 42 is delimited, at the top, by thecoupling surface 44, on which a first and a second preliminary regionG1*, G2* extend, which are made, for example, of germanium and aredesigned to form, respectively, the first and second junction regionsG1, G2. Moreover, the projecting region 22 is delimited, at the top, bya temporary surface S_(p)b, on which a third preliminary region 23*extends, which is made, for example, of germanium and is designed toform the junction region 23. The first, second and third preliminaryregions G1*, G2*, 23* have a thickness of, for example, 0.5 μm.

Next, as shown in FIG. 7 , the second wafer 202 is flipped over and iscoupled to the first wafer 200 so that the first and second preliminaryregions G1*, G2* contact, respectively, the first and second topsurfaces T1, T2 of the first and second filtering metallizations M1, M2,within the filtering window 40, and moreover so that the thirdpreliminary region 23* contacts the exposed part of the first topmetallization 12, within the sealing window 14.

In addition, a bonding process is carried out at a temperature higherthan the melting point of the eutectic alloy that forms the junctionregion 23 and the first and second junction regions G1, G2. In this way,there occurs interaction between germanium and aluminum and consequenttransformation of the first, second and third preliminary regions G1*,G2*, 23*, respectively, into the first and second junction regions G1,G2 and into the junction region 23. Furthermore, the portions of thecoupling surface 44 left exposed by the first and second preliminaryregions G1*, G2*, previously (FIG. 7 ) separated by the first and secondtop surfaces T1, T2 of the first and second filtering metallizations M1,M2 abut upon the latter. There is thus formed, as shown in FIG. 8 , adevice that is the same as the ambient sensing device 50 illustrated inFIG. 2 , but without the hole 25, which is formed subsequent to bonding,using common machining techniques of a deep-silicon-etching type (stepnot shown) so as to obtain the ambient sensing device 50 illustrated inFIG. 2 . In a per se known manner, dicing/singulation operations canthen be carried out.

Finally, it is clear that modifications and variations may be made towhat has been described and illustrated herein, without departing fromthe scope of the present disclosure, as defined in the annexed claims.

For instance, as mentioned previously, the first and/or the secondbottom metallization 10, 30 may be absent.

The exact alignment of the filtering window 40, in particular withreference to the side walls P1-P4 of the first and second filteringmetallizations M1, M2, may vary with respect to what has been described.

The coupling between the projection 22 of the cap 18 and the first topmetallization 12, and hence the lateral sealing of the cavity 20, may beobtained in a way different from what has been described. Likewise, thejunction region 23 may have a shape and arrangement different from theone described.

In general, materials may be used different from the materials describedpreviously. For instance, coupling between the projecting filteringregion and the top metallization structure may be obtained in a waydifferent from what has been described. In particular, the preliminaryregions and the top metallization structure may be made of materialssuch as to enable formation of a metal bonding other thanaluminum-germanium, such as for example a gold-gold or gold-tin bonding.Furthermore, bonding may be not only of a fusion type but also of ananodic type, or of a type selected from among: glass-frit, polymeric ordry-film, etc. In this case, the metallization structure is replaced bya coupling structure, which has, for example, the same shape as themetallization structure described previously, but is made of a materialthat may be different from a metal material, such as a dielectric orsemiconductor material. The coupling structure is bonded to theprojecting filtering region of the cap.

In addition, the cap may not only be made of any semiconductor (forexample, silicon carbide) but also of any substrate currently used inthe manufacture of integrated circuits, such as for example a vitreoussubstrate.

Finally, as mentioned previously, the hole in the cap may have, alongthe axis Z′, a section of variable shape, in which case, with reference,for brevity, to a single channel, the section and/or the opening oropenings have/has an area smaller than the area of the section of thehole that has the minimum area from among the sections of the hole inplanes perpendicular to the direction of extension of the hole.

The various embodiments described above can be combined to providefurther embodiments. Aspects of the embodiments can be modified, ifnecessary to employ concepts of the various patents, applications andpublications to provide yet further embodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

1. A device, comprising: a substrate; a cap on the substrate, the capincluding a primary body and a projecting region that extends from theprimary body; a filtering hole extends through the primary body andthrough the projection region; a coupling structure on the projectingregion of the cap, the coupling structure including: a plurality ofmetallizations on the substrate and between the substrate and theprojecting region; a plurality of filtering channels delimited by theplurality of metallizations, each filtering channel of the plurality offiltering channels is delimited by at least a pair of adjacentmetallizations of the plurality of metallizations and is transverse toadjacent filtering channels of the plurality of filtering channels onopposite sides of each metallization of the plurality of metallizations;and a cavity is between the substrate and the cap.
 2. The device ofclaim 1, further comprising a plurality of junction regions on theplurality of metallizations, and the plurality of junction regions arebetween the projecting region and the plurality of metallizations. 3.The device of claim 1, wherein each metallization of the plurality ofmetallizations includes: a first sidewall; and a second sidewall istransverse to the first sidewall, the second sidewall extends to thefirst sidewall.
 4. The device of claim 3, wherein the plurality offiltering channels are delimited by respective first sidewalls of theplurality of metallizations and respective second sidewalls of theplurality of metallizations that are adjacent to each other and faceeach other.
 5. The device of claim 1, wherein: each filtering channel ofthe plurality of filtering channels includes a first dimension thatextends between at least the pair of adjacent metallizations of theplurality of metallizations; the filtering hole includes a seconddimension that extends across the filtering hole that is greater thanthe first dimension.
 6. The device of claim 5, wherein the filteringhole is circular and the second dimension is a diameter of the filteringhole.
 7. The device of claim 1, wherein the plurality metallizationsincludes at least two metallizations.
 8. The device of claim 7, whereinthe plurality of metallizations includes at least three metallizations.9. The device of claim 1, wherein the cavity is in fluid communicationwith at least one of the plurality of fluid channels and the cavity isdelimited by the projecting region.
 10. A method, comprising: forming amain body including a semiconductor body and a coupling structure withat least three metallizations that laterally delimits at least threechannels; forming a cavity between the main body and a cap, positioningthe at least three metallizations that laterally delimits the at leastthree channels between the semiconductor body and the cap, andfludicially coupling the cavity with at least one of the at least threechannels by mechanically coupling the coupling structure to a projectingregion of the cap projecting from a primary body of the cap; and forminga hole extending through the primary body and the projecting region ofthe cap.
 11. The method of claim 10, further including forming at leastthree junction regions on the projecting region of the cap.
 12. Themethod of claim 11, wherein mechanically coupling the coupling structureto the projecting region of the cap further includes mechanicallycoupling each junction region of the at least three junction regions toa respective metallization of the plurality of metallizations.
 13. Themethod of claim 10, wherein forming the hole extending through theprimary body and the projecting region of the cap fluidically couplingthe hole with the at least three channels further includes forming thehole transverse to the at least three channels.
 14. The method of claim10, wherein forming the hole occurs after coupling the cap to thecoupling structure to the projecting region of the cap projecting fromthe primary body of the cap.
 15. The method of claim 10, furthercomprising forming the projecting region of the cap by removing portionsof the cap.
 16. A device, comprising: a cap includes: a primary body; aprojecting region that projects from the primary body; and a hole thatextends through the primary body and extends through the projectingregion, the hole having a first dimension that extends across the hole;a main body including: a first metallization; a second metallizationspaced apart from the first metallization; a first channel delimited bythe first metallization and the second metallization, the first channelhas a second dimension that extends from the first metallization to thesecond metallization, the second dimension is less than the firstdimension, and the first channel is in fluid communication with thehole; a first junction region is interposed between the firstmetallization and the projecting region, and the first junction regioncouples the first metallization to the projecting region; and a secondjunction region on the projecting region and spaced apart from the firstjunction region, the second junction region couples the secondmetallization to the projecting region.
 17. The device of claim 16,further comprising a second channel spaced apart from the first channeland in fluid communication with the hole, and wherein: the main bodyfurther includes a third metallization spaced apart from the firstmetallization and the second metallization, and the second metallizationis between the first metallization and the third metallization; and thesecond channel is delimited by the second metallization and the thirdmetallization, the second channel includes a third dimension thatextends from the second metallization to the third metallization, andthe third dimension is less than the first dimension.
 18. The device ofclaim 17, wherein the first channel is transverse to the second channel.19. The device of claim 17, wherein the second dimension and the thirddimension are equal to each other.
 20. The device of claim 16, wherein:the first metallization further includes: a first sidewall; and a secondsidewall transverse to the first sidewall, the second sidewall extendsto the first sidewall; the second metallization further includes: athird sidewall that faces the second sidewall; and a fourth sidewalltransverse to the third sidewall, the fourth sidewall extends to thethird sidewall; the first channel is between the second sidewall of thefirst metallization and the third sidewall of the second metallization.